Abstract

Tunneling splittings in the water dimer have been determined by the semiclassical WKB method, based on pathways characterized at the computational level of second-order Møller–Plesset (MP2) theory with basis sets of aug-cc-pVTZ quality. This calculation takes into account all three acceptor tunneling, donor–acceptor interchange, and bifurcationtunneling rearrangements of the water dimer. The tunneling splittings were evaluated as 7.73 cm−1 (large splitting) and 0.42 cm−1 (small splitting), which are in good agreement with the corresponding experimental values of 11.18 cm−1 and 0.70 cm−1, respectively.